Graphite is a layered material formed by carbon atoms stacked in orderly layers in a two-dimensional planar network. Since the force between the stacked carbon layers is relatively weak, a graphite layer can be easily peeled off from other layers to form a thin layer graphite sheet. Graphene is one atomic layer of graphite.
Graphene was first explored in 1947, by P. R. Wallace who calculated the electronic structure of graphene, and found its unique linear dispersion properties. However, for a long time scientists suspected that graphene may not exist in reality, since a two-dimensional planar atomic layer was considered as a part of a three-dimensional structure that cannot stably exist alone. Therefore, graphene was considered a hypothetical structure useful only as a model for description of the physical properties of carbon materials. In 2010, Professor Andre Geim and his student Kostya Novoselov were awarded the Nobel Prize in Physics for their innovative research related to graphene.
Because graphene is non-toxic, and has excellent chemical and thermal properties, including good thermal conductivity, high mechanical strength and other useful characteristics, graphene-based materials have been widely used in various industrial fields, especially the textile field. For example, Chinese Patent No. CN103046151 discloses “Graphene-regenerated cellulose blended fiber and preparation method thereof”. According to the preparation method described in CN103046151, a graphene oxide solution is mixed with a regenerated cellulose solution to obtain “an intermediate of a graphene-regenerated cellulose blended fiber” through a viscose spinning process, and finally a product of graphene-regenerated cellulose blended fiber is thus manufactured through a reduction step of “intermediate of a graphene-regenerated cellulose blended fibers”, wherein in the reduction step, hydrazine hydrate solution with a mass concentration of 1% is selected as a reductant, then at conditions of 20° C., a graphene-regenerated cellulose blended fiber is added in the hydrazine hydrate solution in the bath ratio of 1:100 to reduction for 120 min., and after washing by water and drying, a graphene-regenerated cellulose blended fibers is thus obtained.
As is well known, a hydrazine hydrate solution is a colorless and transparent oily fuming liquid, smells of ammonia, will smoke in humid air and has strong alkalinity and moisture absorption, as well as being classified as a highly toxic substance. It will burn, if exposed to fire or heat. It will cause an explosion, if inadvertently brought into contact with an oxidizing agent. In addition, if a hydrazine hydrate solution is absorbed by a human through, for example, inhalation, ingestion or absorption through the skin, it will be harmful to human health. Repeated skin contact with hydrazine hydrate solution over a long period of time could poison a person working with the solution, such as the operator of the method described in CN103046151, potentially causing dizziness, nausea and other symptoms. Accordingly, the method described in CN103046151, which uses hydrazine hydrate solution as a reductant for reducing “intermediate of a graphene-regenerated cellulose blended fibers” to produce “graphene-regenerated cellulose blended fibers” may be an unsafe process with high risk that is dangerous to an operator.
The present Applicants have filed a number of patent applications related to methods of preparing natural cellulose nonwoven fabric which is harmless to the natural environment, such as patents approved and granted as TW I392779, TW I392780 and TW I392781. These methods use manufacturing processes and conditions that are safe and do not harm the health of operators. Achieving a method of preparing natural graphene cellulose blended nonwoven fabric appears to be urgent and necessary in this technical field.